Label-free electrochemical detection of brain-derived neurotrophic factor based on a novel immune microelectrode array

Brain-derived neurotrophic factor (BDNF) has been shown to play an important role in numerous processes of functional and structural synaptic plasticity in the mammalian central nervous system. In this work, we report a novel immune microelectrode array (MEA) for electrochemical detection of BDNF without labeling step. The chitosan-thionine-multi-walled carbon nanotubes (CS-THI-MWCNTs) composite films as the bio-sensitive film are modified onto the MEA by electrochemical deposition and successfully adopted to immobilize anti-BDNF for the fabrication of electrochemical immune MEA. The THI acted as an electrochemical indicator for the immune response of BDNF. Due to surface-controlled process of THI redox reaction, the increasing formation of anti-BDNF-BDNF immunocomplex resulted in the decreased response currents of THI and the response currents were inversely proportional to the concentrations of corresponding BDNF. The test results of performance revealed that the label-free electrochemical immune MEA had a good stability, selectivity and the limit of detections for BDNF is 5 pg/mL. A linear calibration plot for detection of BDNF was obtained in a wide concentration range from 0.01 ng/mL to 100 ng/mL (r = 0.9995). This novel electrochemical immune MEA has potential applications to detect BDNF for neuroscience research.